GB812292A - Apparatus for the continuous physical and/or chemical treatment of substances - Google Patents

Abstract

<PICT:0812292/III/1> <PICT:0812292/III/2> <PICT:0812292/III/3> Apparatus for the continuous physical and/or chemical treatment of substances, having two or more working stages which are arranged in series and at least one of which is formed by a working unit having a stator directly or indirectly secured to a casing, a rotor and a centre supply chamber surrounded by the stator and the rotor, and a circulatory path being provided from the outlet of the working unit leading to the centre supply chamber of the unit, the arrangement being such that, by adjusting the speed of the through flow of the treated material through the apparatus, the treated material either repeatedly circulates in the working unit by returning from the unit outlet through the circulatory path to the centre supply chamber or flows through the unit without returning through the circulatory path. The treatment may be dispersing, homogenizing or comminuting. The apparatus shown in Fig. 1 comprises three working units each having a rotor disc 10 provided with one or more circular rows of comminuting teeth 11 and a stator 13 provided with one or more circular rows of comminuting teeth 12, the stator being connected to the casing 3 of the apparatus by means of spaced arms 14. Above the working units is an inlet stage having an inlet 1 arranged tangentially of a head piece 2 provided with a base 4 and a ring 5 having an overflow edge 6, the parts 2, 4, 5 acting as a cyclone. Below the working units is a pump impeller 18 disposed within a sieve cylinder 19 and a tangential outlet 20. A removable hopper 16 is arranged between each pair of working units and a hopper 17 between the lowest working unit and the pump impeller. The number of comminuting members of a row of a working unit is greater and the cross-section of the members and the pitch therebetween are smaller than those of a preceding working unit. In the case of a working unit having a plurality of pairs of co-operating rows of comminuting members, the number of members per row becomes larger from the inside to the outside but the cross-section of the members and the pitch therebetween becomes smaller. In operation, the raw material, e.g. wood intended for cellulose pulp, is pumped, mixed with water, into the head piece 2 through the inlet 1 in the direction of the arrow line a. Heavy parts, e.g. metal, stones are retained in the base 4, whereas the water and wood mixture flows over the edge 6. The material which has been more or less disintegrated or refined in the first working unit is thrown out under pressure at the periphery of this unit and flows, in the case of a direct through-flow, along the arrow line a through the first hopper 16 into the second working unit. The material flows from the second working unit along arrow line a to the third working unit. The hopper 17 guides the material from the third working unit to a chamber 26 where it is caught by the impeller 18 and put into a radial/tangential flow which results in an overpressure zone on the inner side of the cylinder 19. At the same time, the water is sucked through the cylinder 19 into a chamber 27 and thence into the outlet 20. The insufficiently refined material which has accumulated within the cylinder 10 is urged upwardly along the arrow line b through a circulatory path 40 and returns to the supply chamber of the third working unit. The material may be returned repeatedly through the path 40 until it has been refined sufficiently to pass through the cylinder 19. The duration of the treatment in the apparatus can be regulated by adjusting the speed of flow of the material through the apparatus. This is achieved by controlling a regulating and closing member in the outlet 20. When the outlet is completely closed, the material is circulated continuously through the individual working units along the closed arrow lines A, B, C. When the outlet is completely open, no circulation takes place along the arrow lines A, B, C. In a modification, Fig. 5 (not shown), the outer row of the stator is constructed as a cylindrical ring provided with apertures, and a hollow space is provided above the stator to receive a heating or cooling medium. In another modification, Fig. 7, the ring 13, which is provided with tearing teeth 31, is secured to a hopper 16 by means of spaced axial crosspieces 30 between which are arranged pivoted closure flaps 33 which open automatically under excess pressure prevailing outside the flaps. In a further modification, Fig. 9, the flaps 33 are replaced by an annular disc 35 suspended on axially displaceable rods 34. The cyclone 2, 4, 5 and/or the sifting device 17, 18, 19 may be omitted. The first working stage may then be formed by a working unit to which material is conveyed by one or more feeding containers in each of which may be fitted a dispersing device. The return of material from a working stage into a preceding working stage could be effected by connections outside the casing. The apparatus may be horizontal or inclined. The apparatus may comprise two or more parts arranged side by side, the material being transferred from one part to another through connecting members, e.g. pumps. Specifications 734,571 and 774,275, [both in Group II], are referred to.